The present invention relates to a former which comprises a press assembly of punches and corresponding dies for pressing metal workpieces into bolts, nuts or other metal parts multistepwise successively more closely to the desired dimensions thereof, and more particularly to a novel and useful apparatus of this type wherein the press assembly is provided with a rolling mechanism operable in timed relation therewith as for threading, to perform press work and rolling work by a continuous process fully automatically.
For example, when bolt blanks are formed with the use of a multi-stage press former by cutting a metal material to a predetermined length and subjecting the cut workpieces to preliminary and several subsequent steps of press work, it is usual practice to collect the blanks and then thread them by a separate process for finishing. However, when the blanks obtained by press forming are threaded by thread rolling as secondary work, there is a considerable interval of time as well as of distance between the press work and the thread rolling, so that there is a need to use a guide pipe, conveyor or the like for supplying the blanks to the rolling apparatus. While the blanks are being so conveyed to the rolling apparatus, the conveyance means can become plugged or like trouble is likely to occur, thereby hindering the smooth transfer of the blanks, resulting in an interruption in the process or accumulation of blanks, and therefore a reduced work efficiency. Presently, therefore, it is impossible to operate the apparatus reliably without an operator. Furthermore, the independent thread rolling apparatus needed for the secondary work must be large-sized, requires additional labor and makes the product costly to produce. Moreover, when thread rolling is resorted to, the thermal effect on the bolt blank is of importance, whereas the lapse of much time involved in the transfer from the press work process to the rolling process entails a drop of temperature, giving rise to difficulty in obtaining high-tension bolts which are resistant to fatigue.